Method and apparatus for forming cup-shaped metal articles

ABSTRACT

A punch and a plurality of dies are mounted for simultaneous movement toward and away from each other. A metal blank is positioned adjacent the dies. As the dies and punch move toward each other, the punch forces the blank through the dies, thus forming the article. As the punch and dies are separated, the formed article is removed from the punch.

[ Dec. 9, 1975 United States Patent [191 Misonoo 1,967,245 7/1934 Hothersall............................. 2,800,813 7/1957 Fischer........... 2,872,887 2/1959 Praturlon.............................. 3,270,544 9/1966 Maeder et Tokyo, Japan FOREIGN PATENTS OR APPLICATIONS 669,678 4/1952 United Kingdom................... 72/349 June 25, 1973 [21] Appl. No.: 373,297

Primary ExaminerRichard J. Herbst Attorney, Agent,

o mn mm Pe m C mo d .m 0% V5 7 .mw T 2 m a TU en da nJ n 0 mm e r HP 4 M or FirmWenderoth, Lind & Ponack ABSTRACT [30] Foreign Application Priority Data June 23, 1972 A punch and a plurality of dies are mounted for simul- Apr. 24, 1973 taneous movement toward and away from each other. A metal blank is positioned adjacent the dies. As the dies and punch move toward each other, the punch forces the blank through the dies, thus forming the ar- 2 n m M2 L C St Um 1] 21 55 [l [58] Field of Search 72/347, 348, 349, 408,

72/344 346; 113/120 H ticle. As the punch and dies are separated, the formed article is removed from the punch.

References Cited UNITED STATES PATENTS 5 Claims, 6 Drawing Figures 628,043 Sperber................................. 72/408 US. Patent Dec. 9 1975 Sheet 1 of 3 3,924,436

US. Patent Dec. 9 1975 Sheet 2 of3 3,924,436

.5. Patent Dec. 9 1975 Sheet 3 of 3 STROKE (mm) |QO o IQO CRANK ANGLE METHOD AND APPARATUS FOR FORMING CUP-SHAPED METAL ARTICLES BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for forming a cup-shaped metal article.

For the most part, in the past the manufacture of cupshaped metal articles have been accomplished by a drawing operation. However, relatively deep cupshaped metal articles cannot be manufactured by a single drawing operation. The maximum ratio of wall height to cup diameter is l to 1.3 in a single drawing operation. Accordingly, it has been necessary to attempt to perform multiple drawing operations on a single article. However, this has certain disadvantages. Specifically, desired brightness of the wall surface cannot be obtained. Further, the thickness of the wall of the redrawn article is the same as or greater than the thickness of the bottom of the article. This is undesirable since generally cup-shaped metal articles such as beverage cans do not require that the wall thickness be as great as the bottom thickness.

Thus, the practice has developed to form the finished cup-shaped article from a drawn cup-shaped metal blank by means of dies and a punch. Such operations have generally involved the forming of the finished article by passing the blank through a plurality of, such as two or three, fixed dies. Furthermore, the dies are arranged so that the article is not simultaneously contacted by any two adjacent dies. If the cup is acted upon simultaneously by two fixed dies, the article is formed at a different rate at each die stage, such that a slackness occurs in the wall of the article between the dies, thereby resulting in a breakage of the wall. Since the maximum reduction ratio at one die stage is approximately 40 to 50 percent, it is necessary to separate the dies in a geometrical progression for a relatively deep finished article. Devices for carrying out such a forming ope ration generally include a movable forming punch, a plurality of fixed dies, a cup infeed mechanism, a cup outfeed mechanism, and a doming punch for forming the bottom of the article. The punch stroke is dependent upon the space between dies, the space for the cup infeed mechanism, and the space between the last die and the doming mechanism. The deeper the cup to be formed the longer the stroke of the punch and thus, the more difficult it is to form an article accurately at high speeds.

In all such previous forming methods, the dies have been fixed and only the punch is moved. For high speed production, it is obviously desirable to shorten the stroke of the punch.

SUMMARY OF THE INVENTION With the above discussion in mind, it is a primary object of the present invention to provide a method and apparatus for forming cup-shaped metal articles at high speeds and with high product quality. p

It is a further object of the present invention to provide such a method and apparatus wherein thepunch stroke is shortened approximately by half.

It is a yet further object of the present invention to provide such a method and apparatus whereby it is possible to stretch the wall of the article between dies while the article is being formed simultaneously at two dies.

It is a still further object of the present invention to provide such a method and apparatus whereby a finished cup-shaped article may be removed from the punch without damage to the bottom of the article.

The above objects are achieved in accordance with the present invention by providing a mechanism which simultaneously moves the dies and punch toward each other, thereby shortening the necessary overall stroke by half.

The above objects and features will be made clear from the following detailed description taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view with portions broken away of a preferred embodiment of an apparatus in accordance with the present invention;

FIG. 2 is a partial cross-sectional view of the dies employed in the apparatus of FIG. 1;

FIG. 3 is a cross-sectional view of the punch device employed in the apparatus of FIG. 1;

FIG. 4 is a schematic view of a blank infeed mechanism employed in the apparatus of FIG. 1;

FIG. 5 is a schematic illustration partially in crosssection of the apparatus for removing the finished article from the punch; and

FIG. 6 is a graphical illustration of the various locations of the elements of the apparatus of FIG. 1 during one cycle of operation.

DETAILED DESCRIPTION OF THE INVENTION With reference to FIG. 1, a preferred embodiment of the overall device of the present invention will be described.

A frame 10 has an upper slideway surface 11 thereon. A block 20 containing dies 21 and a block 30 containing punch 31 are mounted on slideway 11 for movement toward and away from each other.

A main drive shaft 12 is driven by suitable driving means [not shown]. Shaft 12 has pinions 13 attached thereto which engage with suitably mounted gears 14. Gears 14 are connected to a crank 15 which is connected to connecting rods 16 and 17. Connecting rods 16 and 17 are pivotally connected adjacent the mid points of links 18 and 19 by pins26 and 36. The bottom ends of links 18 and 19 are pivotally mounted to frame 10 by pins 25 and 35. The upper ends of links 18 and 19 are pivotally attached to links 24 and 34 by pins 27 and 37. Links 24 and 34 are respectively pivotally attached to die block 20 and punch block 30.

By the above arrangement, rotation of shaft 12 causes rotation of gears 14 such that crank 15 causes connecting rods l6.and 17 to either move toward one another or away from one another. Accordingly, die block 20 and punch block 30 are accordingly moved toward one another or away from one another along slideway 11.

In FIG. 2 die block 20 and dies 21 are shown in more detail. Die block 20 has a frame 22 on which are mounted three dies 21a, 21b and 21c and a dome forming mechanism 23. The intervals between the dies are determined by the desired reduction ratio of the wall thickness of the finished article.

FIG. 3 illustrates in more detail the form of punch 31. It will be noted that inwardly and coaxially of punch 31 is a knockout punch 32 which is movable outwardly of the end of punch 31. The article contacting end of punch 31 and knockout punch 32 is as desired to form 3 the shape of the bottom of the finished article and to operate in cooperation with doming mechanism 23.

FIG. 4 schematically illustrates a mechanism for feeding blanks to the device. A magazine 71 contains a plurality of blanks. A finger 74 is attached to die block frame 22 and moves therewith. Movement of finger 74 rotates a lever 72 at a predetermined interval and angle to charge cup blanks into a cup holder 73 positioned in front of the dies.

FIG. 5 schematically illustrates a device for operating knockout punch 32 to remove the finished article from punch 31 after the article is formed. A crank 55 rotates synchronously with main crank by means of a suitable interconnection such as chain 53 and gear 54. Crank 55 is connected through a link 46 with one end of a link 44. Link 44 pivots adjacent the middle thereof around a fulcrum pin 49. The other end of link 44 has a sliding connection engaged on a connecting pin 50 of knockout punch 32. It will be apparent that as crank 55 rotates, link 44 causes relative rightward or leftward movement [as viewed in FIG. 5] of knockout punch32. Additionally however, to facilitate this movement and to avoid interference with the punch 31, means are provided for a timed regulatory positioning of the location of the fulcrum pin 49. Specifically, fulcrum 49 is attached to a connecting rod 47 of a piston movable in a chamber 42 of a cylinder assembly 40. A second chamber 41 of cylinder assembly 40 has therein a piston the connecting rod 46 of which is attached to the frame of the device. It will be apparent that the selective and sequentially timed introduction of a fluid into chambers 41 or 42 from reservoir 43 will cause rightward or leftward movement [as viewed in FIG. 5] 0f fulcrum 49. This movement will be timed in a manner apparent to those skilled in the art to coincide with movement of knockout punch 32 with respect to punch 31 to avoid interference between punch 31 and knockout punch 32.

A more detailed explanation of the operation of the device will now be made. Assume initially that die block and punch block 30 are at their most spaced apart positions. Drive shaft 12 is rotated to cause rotation of gears 14 and crank 15. As crank 15 rotates, die block 20 and punch block 30, due to the movement of connecting rods 16 and 17 and links 18 and 19, are caused to approach each other. In the meantime, an article blank 80 has been positioned in holder 73 adjacent dies 21. As die block 20 and punch block 30 approach each other, punch 31 with knockout punch 32 in the withdrawn position of FIG. 3, force blank 80 into the first die 2 1a and performs a first forming operation. The movement of die block 20 and punch block 30 toward each other continues with the blank sequentially being passed through dies 21b and 210, thereby continually forming the finished article. As the article passes through die 21c and conforms to the outer shape of the punch, it finally comes to rest against doming device 23 at which time the bottom of the article is formed. Immediately thereafter, continued rotation of crank 15 causes connecting rods 16 and 17 and therefore die block 20 and punch block 30 to separate. As this separation begins, rotation of crank 55 has reached the point that link 44 causes knockout punch 32 to withdraw from punch 31, thereby initiating removal of the finished article from punch 31. This removal operation is completed by the time punch block 30 returns to its initial position. After removal of the finished article,

4 a new blank is fed to holder 73 to initiate the succeeding operation.

FIG. 6 illustrates the angular position of the various elements of the invention with regard to one example of stroke dimension. The thick solid line represents the position of knockout punch 32. The dotted lines represent the positions of the doming device 23 and punch 31. For the first of rotation of crank 15, knockout punch 32 moves precisely with punch 31. From a crank rotation of 180 to 240 knockout punch 32 moves outwardly from punch 31. After an angular rotation of 240 of crank 15, knockout punch 32 rapidly returns to its position within punch 31 at a crank rotation angle of 310 and thereafter moves with punch 31 back to the initial starting position. The operation is achieved with the cylinder assembly 40 selectively moving fulcrum pin 49. If such movement does not occur, the position of knockout punch 32, without interference from punch 31, would be indicated by the thin solid line in FIG. 6. Specifically, assembly 40 moves fulcrum 49 toward die block 20 during the punching operation and away from die block 20 during the withdrawal movement of die block 20 and punch block 30.

The following table shows the results of a forming op eration employing the apparatus of the present invention. It will be apparent that in accordance with the present invention it is possible to stretch the article wall between dies even when the article is being simultaneously formed at two dies.

It is to be understood that various changes and modifications can be made to the specific apparatus described without departing from the spirit and scope of the present invention.

What is claimed is:

l. A method of forming cup-shaped metal articles by means of at least one die and a punch, said method comprising:

positioning a metal blank adjacent said at least one die;

simultaneously moving said punch and said at least one die from spaced apart withdrawn positions thereof toward each other to adjacent forming positions thereof, thereby causing said punch to force said blank through said at least one die and forming said metal article;

simultaneously moving said punch and said at least one die away from each other; and

removing said thus formed metal article from said punch, said step of removing said formed metal article from said punch comprising moving a knockout punch which is coaxially positioned within said punch longitudinally outwardly of said punch toward said at least one die to a position beyond said forming position of said punch.

2. A method as claimed in claim 1, wherein said at least one die comprises a plurality of dies, and said punch forces said blank through each of said plurality of dies.

3. A method as claimed in claim 2, wherein said blank is simultaneously passed through two adjacent of said plurality of dies.

4. An apparatus for forming cup-shaped metal articles from a metal blank, said apparatus comprising:

a frame having a slideway surface thereon;

a punch and at least one die mounted to move toward and away from each other on said slideway surface;

means for selectively positioning a metal blank adjacent said at least one die;

means for simultaneously moving said punch and said at least one die from spaced apart withdrawn positions thereof toward each other to adjacent forming positions thereof and for causing said punch to force said metal blank through said at least one die, thereby forming said cup-shaped metal article; and

means for removing the thus formed cup-shaped metal article from said punch, said means for removing comprising a knockout punch coaxially and longitudinally movably positioned within said punch, and means for moving said knockout punch longitudinally outwardly of said punch toward said at least one die to a position beyond said forming position of said punch.

5. An apparatus as claimed in claim 4, wherein said at least one die comprises a plurality of dies. 

1. A method of forming cup-shaped metal articles by means of at least one die and a punch, said method comprising: positioning a metal blank adjacent said at least one die; simultaneously moving said punch and said at least one die from spaced apart withdrawn positions thereof toward each other to adjacent forming positions thereof, thereby causing said punch to force said blank through said at least one die and forming said metal article; simultaneously moving said punch and said at least one die away from each other; and removing said thus formed metal article from said punch, said step of removing said formed metal article from said punch comprising moving a knockout punch which is coaxially positioned within said punch longitudinally outwardly of said punch toward said at least one die to a position beyond said forming position of said punch.
 2. A method as claimed in claim 1, wherein said at least one die comprises a plurality of dies, and said punch forces said blank through each of said plurality of dies.
 3. A method as claimed in claim 2, wherein said blank is simultaneously passed through two adjacent of said plurality of dies.
 4. An apparatus for forming cup-shaped metal articles from a metal blank, said apparatus comprising: a frame having a slideway surface thereon; a punch and at least one die mounted to move toward and away from each other on said slideway surface; means for selectively positioning a metal blank adjacent said at least one die; means for simultaneously moving said punch and said at least one die from spaced apart withdrawn positions thereof toward each other to adjacent forming positions thereof and for causing said punch to force said metal blank through said at least one die, thereby forming said cup-shaped metal article; and means for removing the thus formed cup-shaped metal article from said punch, said means for removing comprising a knockout punch coaxially and longitudinally movably positioned within said punch, and means for moving said knockout punch longitudinally outwardly of said punch toward said at least one die to a position beyond said forming position of said punch.
 5. An apparatus as claimed in claim 4, wherein said at least one die comprises a plurality of dies. 